Californian Peter Murphy sent in a list that almost rivaled Ms. vos Savant's in its comprehensiveness. "I've been collecting this list for years," he wrote. Mr. Murphy broke down his recommended knowledge into 14 categories that ranged from practical skills (hang a picture) to the artistic (recognize and "know" 20 great musical works and 24 great works of art) to "fun." (Raise one eyebrow. Use pig Latin. Eat with chopsticks.)

Many readers mentioned the importance of basic skills that have come in handy throughout their lives. Write legibly, always count your change, and read the directions, advises Jack Bullock. Be able to balance a checkbook and avoid credit-card debt, recommends Ann Kelly.

"As a single mother I made sure my daughters knew how to stop the water inflow to a toilet that was about to overflow," writes Rosemary Bolza. "In fact, whenever I had occasion to open the tank to do something with the toilet, I would call them around for a lesson. While they may have groaned at the time, they have all grown into women who are willing to take on difficult tasks."

A number of readers discussed the personal qualities that young people need in order to have good relationships with others. "Good manners can help you acquire a job, get an apartment, find a bargain, register for a class, and get any kind of help," says Terrie Rowley, who adds, "Bad manners can prevent a lot of good things from happening."

"Be able to concede an argument without anger or resentment," advises Alistair Budd.

In the same vein, Ann Kelly adds: Know how to apologize and accept an apology honestly and gracefully.

"Most of what an 18-year-old should know before [he or she] leaves home should have been learned in kindergarten," writes Arthur Bradbury. "Honesty, fair play, integrity, acceptance of others, how to be a good listener, respect for themselves and others.... The most important things are to care and have a positive attitude, and to laugh."

Joyce Robertson reports that when she was in her teens, she received wise counsel from both her grandmothers. One taught her the deeper meaning of smiling. "When I was 15, I broke my two front teeth and had to wait a few years to get caps put on them. My grandmother came into the bedroom where I was crying and said, 'Now, dear, I want you to promise me something. You have always been known by your beautiful smile. Don't ever try to cover it up. A smile is more than a pretty set of teeth. It is an expression of joy and caring for others.' "

Then, when Ms. Robertson was heading to college, her other grandmother talked with her about being herself  and what that meant. "She said: 'If you really know who you are and what you are, you'll never want to copy others or attempt to justify their actions by imitation. Be pleased with yourself, and you'll be sure to please those who are kindred spirits.' "

A reader who identified herself only as Chris also believes that finding and cultivating "kindred spirits" may enrich a person's experience for a lifetime. "You can't teach your kid everything, but if they know how to make friends, they will always have someone to turn to when they come across something you could not prepare them for," she says. "Friendship can also see you through the hard times, and it gives you someone to share the good times."

It's easy to pass along advice, but will the recipient take it to heart? That's the big question, points out Charlotte Stark. "Our advice is sometimes taken  sometimes not for a long time, sometimes never."

Maybe some things have to be learned through experience. That's been the case for Daniel Lei, a 20-something who e-mailed from Shanghai.

He writes: "When I was a teenager, I asked myself such questions [as]: What is the secret of happiness and what kind of a life shall I pursue? At that time I was poor. I [had] a goal  a solitary aim  to be a rich man.

"I told myself that when I have big money, I could give my parents a good life, I could help the people in trouble. So I began to study hard to get a good job, step by step to reach my aim."

It wasn't too long before Mr. Lei found that when he spent all his time studying, he didn't have time for his family or friends.

"I realized that even if I was rich, I would not be happy," he says. "Happiness is not some concrete things, but the attitude about your life.

"Maybe someone will say that a person at 18 needs to know how to manage money ... and so on. Yes, money [and] skills are useful, but we must know that they [are] only the tools to get happiness, not the ultimate goal."